Rotary armature electromagnet



April 1, 1969 a. Y. zHx-:zMER ET AL RQTARYl ARMATURE ELECTROMAGNET Filed Jan. v, 196e United States Patent O U.S. Cl. 335-276 7 Claims ABSTRACT F THE DISCLOSURE An electromagnet having a Z-shaped core including a rod with a coil wound thereon and pole shoes on the ends of the rod, there being a pivotally mounted Z-shaped Iarmature at the center of the rod and embracing the coil, the armature having arms extending in opposite directions on opposite sides of the rod facing the shoes and dene working gaps therewith.

The present invention relates to rotary-type electromagnets, mainly D.C. electromagnets, with a symmetrical magnetic circuit, said electromagnets being designed for use in electric devices, especially in relays and contactors as well ,as in electromagnetic drives.

Known in the art are electromagnets whose core and armature are symmetrical with respect to the rotation axis, said electromagnets having radial or axial direction of the magnetic flux in the air gaps with respect to the rotation axis of the armature and transverse movement of the armature poles in the air gaps with respect to the magnetic flux direction.

The conventional electromagnets have a constructionally balanced symmetrical armature. They dilfer from plunger and straight-pull electromagnets by possessing, for the major part of switching devices and drives, an unfavorable shape of the pull characteristic. Its rise slows down and even changes sign during the pull-in of the armature, since at a constant air gap in the above systems and a given number of ampere-turns the increase of the pulling power is determined Iby the increment of overlap of the armature poles and the core perV unit of angular displacement of the armature. The leakage fluxes in such electromagnets are not employed for producing `an operating pull, and the air gap in the magnetic circuit remains constant while the armature is in closed position. All these factors pose the necessity of power increase for obtaining the required pulling forces and therefore an increase of the electromagnet size.

The electromagnets of this type with axial direction of the flux in the .air gap produce considerable mechanical stresses along the axis and require the use of journal bearings which are subject to wear. The wear resistance of the electromagnets can be reduced by complex bearing arrangements but this makes them more complicated.

Furthermore, the known electromagnets change their electromagnetic characteristics under the action of external magnetic fields, which adversely aifects their functioning.

An object of the present invention is to eliminate the abovementioned disadvantages.

Another object of this invention is to provide an e1ectromagnet which is simple in design, and is shockand vibration-proof in operation.

Still another object of the invention is to provide an electromagnet possessing high wear resistance.

It is still another object yof the present invention to provide an electromagnet ywhich is not subject to the influence of external magnetic fields and which has smaller size in nCC comparison with electromagnets of the same power designed for the same purposes.

With the above and other objects in view the invention consists in a novel electromagnet whose core and armature are arranged in such a way and have such form that the projection of the magnetic liux in the magnetic circuit upon the plane normal to the rotation axis of the armature has a ligureof eight shape.

It is expedient that the core with the pole shoes be of a Z-shape in a plane normal to the rotation axis of the armature.

A favorable solution is achieved if the electromagnet armature is made two-armed with respect to the rotation axis and Z-shaped, and the middle portion thereof in the section perpendicular to the armature axis may have a closed form and encloses the core.

It is desirable that the armature and the core be symmetrical with respect to the rotation axis of the armature.

The faces of the pole shoes of the core and armature, with the magnetic circuit closed, are normal or oblique to the axis of the magnetic iux at the place of the pole faces contact.

Other objects and advantages of this invention will be apparent from the following description and the accompanying drawings, in which:

FIG. 1 is a schematic elevation view of a D C. electromagnet;

FIG. 2 is a cross section of the electromagnet of FIG. 1, taken along the line II-II; and

FIG. 3 is a schematic elevation view of a D.C. electromagnet with oblique poles.

The electromagnet consists of the following parts and units: a rotary-type magnetic system with a Z-shaped core 1 and a two-armed Z-shaped armature 2, having a closed form in the middle portion thereof and embracing the core 1 and a coil 3, said coil being wound directly on the core 1. Pole shoes 4 and 5 of the core 1 are arranged on lboth sides of the coil 3. The operating surfaces of said pole shoes are parallel to the longitudinal axis of the coil 3 `(FIG. l) and symmetrical with respect to the longitudinal and transverse taxes of said coil. In order to obtain the desirable shape of the pull characteristic it is possible to arrange the operating surfaces of the core 1 at a slight angle relative to the longitudinal axis of the coil as it is presented in FIG. 3. The armature 2 rotates with respect to the core 1 on shaft axles 6. The rotation axis of the armature 2 coincides -with the transverse axis of the core 1 and coil 3, said axis being parallel to the operating surfaces of the pole shoes 4 and 5 of the core 1 and is symmetrical with respect to said surfaces.

The magnetic circuit of the electromagnet has a ligure-of-eight projection in a plane normal to the rotation axis of `the armature 2. It consists of the following separate parts: the core 1 bearing the coil 3, two symmetrical air gaps, and the .armature 2, having a closed form and embracing the core 1 with the coil 3 in the middle portion thereof.

The core 1 and the armature 2 are symmetrical with respect to the rotation axis of the armature.

Such contiguration of the magnetic circuit allows a favorable pull characteristic for electromagnets of switching devices and electromagnetic drives to be obtained the characteristic curve constantly rising -with the decrease of the air gaps.

This is achieved due to the coaxial flux direction in the air gaps with respect to the rotation axis of the armature, and also due to the armature movement along the magnetic tlux until a complete contact of the poles of the armature 2 and core 1 is achieved.

External magnetic fields do not influence the make characteristics of the electric app tromagnets of the present invention.

aratus employing elecf This is achieved due to the screen effect of the armature embracing the core.

The symmetrical design of the core and armature with respect to the rotation axis of the armature allows manufacturing electric apparatus which is reliable in operation under vibration and shock conditions.

What is claimed is:

1. An electromagnet comprising a core including a rod portion having opposite ends, and pole shoes on said rod portion projecting from said ends in opposite directions to dein a generally Z-shape for the core, a coil wound on the rod portion between the shoes, and an armature including a central frame portion embracing the coil and supported for pivotal movement about an axis extending` transevrse of the rod portion midway thereof, and a pair of arms extending from the frame portion in opposite directions on opposite sides of the rod portion such that each arm faces a respective pole shoe -with a gap therebetween, the arms and said frame portion defining a substantially Z-shape for the armature which is a mirror reflection of the Z-shape of the core.

2. An electromagnet as claimed in claim 1 wherein said pole shoes have the approximate shape of rectangular prisms.

3. An electromagnet Ias claimed in claim 1 comprising a pair of axles supporting the armature for pivotal movement about said axis, said rod having a longitudinal axis, said axles being xably supported relative to the rod such that the axis of pivotal movement of the armature intersects the longitudinal axis of the rod at a point which is the center of spatial symmetry of the armature, core, coil and gaps. v

4. An electromagnet as claimed in claim 3 wherein said coil is coaxially wound on the core.

5. An electromagnet as claimed in claim 1 wherein each of said arms of the armature includesaa part facing the associated pole shoe which is parallel to the longitudinal axis of the coil with the frame in a normal unrotated position.

6. An electromagnet Vas claimed in claim 1 wherein each of said arms of the armature includes a part facing the associated pole shoe which is inclined with respect to the longitudinal `axis of the coil with the frame in a normal unrotated position.

7. An electromagnet as claimed in claim 1 wherein said rod is cylindrical.

References Cited UNITED STATES PATENTS 541,471 `6/1895 Corey 335-279 X 1,273,820 7/1918 Cahusac 335-276 2,436,354 2/1948 Burke et al. 335-276 X 3,098,135 7/1963 Farmer 335-281 G. HARRIS, Primary Examiner.

U.S. Cl. X.R. 

